1. Field of the Invention
The present invention relates to a semiconductor light-emitting element such as a vertical cavity surface emitting laser (VCSEL) and a method for manufacturing the same.
2. Description of the Related Art
The vertical cavity surface emitting laser (hereinafter simply referred to as the surface emitting laser) is a semiconductor laser that is configured to oscillate light perpendicularly to a surface of the substrate so as to emit light in the direction perpendicular to the surface of the substrate. For example, disclosed in Patent Literature 1 (Japanese Patent Application Laid-Open No. Hei 07-297476) is a semiconductor laser device in which an active layer is sandwiched between Bragg reflectors, and the active layer is grown along an axis which is tilted by 5° to 10° or more from the [0001] axis.
For example, the surface emitting laser has reflectors that are opposed to each other with a light-emitting layer sandwiched therebetween, and the mutually opposed reflectors form a resonator. In the surface emitting laser, the reflector can be formed, for example, by alternately depositing, a plurality of times, two thin films having different refractive indices to each other. To reduce the lasing threshold value (operation voltage) of the surface emitting laser, it is preferable that the light reflectivity of the reflector should be high, and the light absorptivity of the reflector should be low.
Furthermore, to manufacture a semiconductor light-emitting element, without being limited to the surface emitting laser, so as to improve the extraction efficiency of light emitted from the element, there may be formed a light reflecting layer on a surface of the light-emitting layer opposite to the light extraction surface. This light reflecting layer also preferably has a high reflectivity.
On the other hand, to manufacture a light-emitting element from a hexagonal system semiconductor material, it is known that the semipolar plane of a substrate used for growth is employed as a crystal growth plane in order to grow a semiconductor structure layer on the semipolar plane. This is because the use of the semiconductor structure layer grown on the semipolar plane makes it possible to inhibit the occurrence of an inner electric field within the light-emitting layer and improve the efficiency of light emission as compared with a case where a semiconductor structure layer grown on a polar plane such as the c plane (i.e., (0001) plane) is used.